hi,You can use the $40 voucher on all Urban Decay products except for the palettes (like Naked Palette). So you can use it on UD brushes. The Sephora store at Ion carries the most comprehensive range of UD brushes whereas the store at Ngee Ann City only has the eyeshadow brushes. You can also use it on TooFaced, Hourglass etc. You can find the list of eligible brands in the store.

Aside from the UD brushes, you can also consider their eyeliner pencils, lipglosses or Urban Decay Primer Potion.